Operators of the St. Lawrence Seaway System that links the Great Lakes and the North Atlantic say cargo shipments are up this spring.
The seaway reports that total cargo shipments for March 22 to May 31 were 8.9 million metric tons, up 3.7 percent from the same period in 2011.
Seaway officials say commodities used in the steel and construction industries are behind the increase.
Seaway trade development director Rebecca Spruill said in a statement Tuesday that so far this year, total tonnage is up about 5 percent over 2011.
She says there have been double digit increases in coal and iron ore, and a general cargo increase of about 7 p.m.